This invention relates to a method of molding articles, and in particular to molding articles from recycled materials. More specifically, this invention relates to a process for molding nonhomogeneous articles from various recycled materials so that the finished article has given areas or volumes that exhibit different mechanical properties.
There is a great need to reuse materials such as thermosetting plastic, rubber and the like in order to avoid many of the environmental problems associated with the disposal of these materials. Some processes such as those disclosed in U.S. Pat. Nos. 5,145,617, 5,075,057, and 5,055,350 have been devised for making articles from used plastics. However, for the most part, these processes are energy dependent in that they require the use of heat and/or pressure to achieve the desired result.
Other processes, such as the process described in U.S. Pat. No. 5,106,880, are dedicated to recycling very specific materials. In the noted patent, cellulose fibers are combined with cellulose starch in the presence of a gas generating agent to form a foam matrix. The foam material produced by this process, while useful, does not possess high tensile or compressive strength.
U.S. Pat. No. 4,443,286 to Ikeda et al. involves a process for manufacturing automobile cushions from polyurethane. Initially, a sheet of polyurethane is placed between a pair of forming dies and the sheet is coated with recycled polyurethane foam chips. The chips are bonded to the sheet using an adhesive while at the same time being compressed between the dies. Here again, the process requires the use of pressure and does not utilize recycled material.